The number of unsafe abortions is rising around the world, while what appeared to be a steady decline in abortion rates in the 1990s has stalled, according to an authoritative new report.

The analysis from the Guttmacher Institute in the US, which looks at trends since other major global analyses in 1995 and 2003, will dismay both campaigners against abortion and those who fight for improved maternal health.

Half of all abortions (49% - up from 44% in 1995) are now unsafe. They are carried out by somebody unqualified in unsuitable premises and can end in infection or haemorrhage and death. Almost all abortions (97%) in Africa and Latin America (95%) are unsafe and 40% of those in Asia.

Banning abortion does not reduce the numbers of women who attempt it, say the authors of the report. The abortion rate is higher in regions where it is illegal and therefore usually unsafe - at 29 per 1000 women of childbearing age in Africa and 32 per 1000 in Latin America, where most countries forbid it. That compares with 12 per 1000 in western Europe and 19 in north America. The rate in the UK is around 16 per 1000.

A great and increasing unmet need for contraception is part of the problem, say Dr Gilda Sedgh and colleagues from the Guttmacher, who wrote the report. The stalling decline of abortion occurred in tandem with a stalling roll-out of contraception to couples who want it. "It is attributed to funding for family planning not keeping pace with demand as the size of the population is growing and women and couples want to have smaller families," said Sedgh. An estimated 215 million women want contraception but cannot get it.

Cultural and religious opposition to abortion prevents the issues being properly discussed, let alone tackled, said Richard Horton, editor of the Lancet medical journal which published the report online. Yet the complications of abortion are responsible for 13% of maternal deaths and reducing those deaths is now a major global focus.

"The mere mention of the word 'abortion' in the journal leads to a phenomenal and visceral reaction against even discussing the issue," Horton told journalists.

He chaired a working group on information and accountability of a commission on women's and children's health last year, which included the issue of abortion in its final report.

"American representatives explicitly came to me and asked me to remove the word abortion from our draft," he said. "Even under an Obama administration, it is not possible to have an open discussion about abortion in international agencies and commissions. This stigmatisation, this censorship around the issue of abortion, is what is causing the enormous distortion of priorities in women's health today."

The Guttmacher report says the abortion rate worldwide dropped from 35 to 29 per 1000 women between 1995 and 2003 but has hardly moved since. There were 43.8 million abortions in 2008, which is 2.2 million more than in 2003, because of the increasing population. The numbers in the developed world dropped by 0.6 million but those in the developing world rose by 2.8 million.

Eastern Europe has a higher abortion rate than Africa. Although it dropped from 90 per 1000 in 1995, when legal abortion was routine in some countries, it was still at 43 per 1000 in 2008 - only just lower than 44 per 1000 five years earlier.

A commentary in the Lancet says the Guttmacher estimates of abortion numbers are likely to be conservative, "particularly in legally restricted settings where there is tremendous incentive to conceal abortion use and provision."

Almost the entire global burden of women's deaths from abortion occurs in Africa, Asia and Latin America. "Somehow we typically act as if this were neither surprising nor troubling," write Beverly Winikoff and Wendy Sheldon from Gynuity Health Projects in New York. Yet the women and the procedures needed to save their lives are the same as in north America or Europe.

"If a lack exists, it is a lack of caring; a willingness to sacrifice lives to an ideological moral high ground, to social acceptability or to the maintenance of a political comfort zone," they say.